The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Vehicles use powertrain systems to generate tractive torque. Known powertrain architectures include internal combustion engines that transfer torque through a transmission to an output member. Known hybrid powertrain architectures include internal combustion engines and torque machines that transfer torque through a transmission device to an output member. The output member can be coupled to a driveline of a motor vehicle for transferring tractive torque thereto. The torque machines can include electric machines that are configured to operate as torque motors and electric power generators.
Known control systems monitor inputs from the vehicle, the powertrain and an operator and provide operational control of the powertrain, including controlling the engine state and controlling a transmission range to manage outputs of the transmission, including torque and rotational speed. Known control systems for hybrid powertrains can additionally control torque machine(s) and regulate power interchange between an energy storage device and the torque machine(s) to manage outputs of the transmission, including torque and rotational speed.
An operator operates a vehicle and powertrain by commanding a key-on state. Known control schemes for powertrain and hybrid powertrain systems include operating an engine in an engine-off state during the key-on state. The engine-off state comprises the engine unfueled and not spinning, which can occur during ongoing vehicle operation when the vehicle is in the key-on state. Known powertrain operation includes transitioning the internal combustion engine between the engine-on and engine-off states during the key-on state. Known control schemes include starting the internal combustion engine by cranking and fueling it using the powertrain system. Known engine starting events occur in response to the operator commanding a key-on state. Known engine starting events occur subsequent to an autostop command during powertrain operation in the key-on state, e.g., in response to an operator torque request.
It is known that an engine may have internal friction and pumping losses that affect engine torque, including engine torque immediately subsequent to engine start. It is known that a newly-assembled, i.e., ‘green’ engine can have substantial internal friction. It is known that an engine can have substantial internal friction at low ambient temperatures subsequent to a cold soak. It is known that a control scheme may not detect engine firing, i.e., may not detect the engine is producing positive torque subsequent to a start event.